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I bought a house in Massachusetts (USA) that was built around 2009. It has a generator with a service rated automatic transfer switch (ATS) connected to a main panel that is set up as a main panel (NOT a sub panel). I don't know if the generator was there from the start, or added later.

Everything I have read seems to indicate that my main panel should be set up as a sub panel with neutrals and grounds separated, green neutral bond screw removed, and the GEC + all bonding should take place in the ATS panel. None of this is currently the case.

I'm wondering if this is or ever was code compliant? I have an inquiry out to my town's electrical inspector. I was hoping to also get feedback from the great minds of the internet!

Note that my grounding electrode is my copper water pipe and there are no ground rods by the service entrance. My meter is up at the street ~200 feet away from the house. The meter has ground rods, bonds ground and neutral, and has a 200 amp breaker in it. Three wires run to my house (2 hot 1 neutral) in underground PVC conduit. My inspector confirmed that everything in this paragraph was inspected and met code when inspected in 2009.

Here is a diagram that I made of the current configuration of the ATS + main panel:

Main Panel and ATS configuration

Update 1/20/22: Here is a photo of the ATS labeling on the door as requested by @ThreePhaseEel:

Picture of ATS label on inside door

Update 1/23/22: The model number for the Briggs & Stratton ATS is 071025 (rev 00)

kr4sh2
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    Good question. Yes, it pivots on a) on when NEC changed that requirement, and b) when your state adopted that version of NEC. – Harper - Reinstate Monica Jan 17 '22 at 19:24
  • Who is your electric utility? – ThreePhaseEel Jan 17 '22 at 23:50
  • My electric utility is National Grid – kr4sh2 Jan 18 '22 at 00:11
  • Can you post photos of the labeling on your transfer switch please? – ThreePhaseEel Jan 21 '22 at 03:35
  • @ThreePhaseEel I just added a photo of the labeling on the inside door of my ATS. I think there are also labels on the inside walls of the panel as well. Let me know if those are relevant and I can snap a pic this weekend. – kr4sh2 Jan 21 '22 at 03:51
  • As it was explained to me by our electrical inspector the main panel is where power enters your system (where the meter is connected). Since it connects to the transfer panel it is considered the main panel and all others are sub including the main breaker panel in the home. All grounds and bonding etc must be done in the transfer panel. – Gil Jan 21 '22 at 18:00
  • @Gil This is basically my understanding based on current code as well, but with more specifics around the location of the first disconnect being what defines where grounding/bonding should take place. Anyway, my question is if there is anything in current code that allows for my setup as some sort of exception, OR if my current setup was ever code compliant around 2009. I believe MA adopts NEC state wide (not different per town) and it sounds like they adopt new versions quickly. If anyone has more clarity on that please correct me if I'm wrong. – kr4sh2 Jan 21 '22 at 18:39
  • @kr4sh2 -- is your service to the metering point overhead or underground, and likewise for the feed from the metering point to the house? – ThreePhaseEel Jan 22 '22 at 00:18
  • @ThreePhaseEel The power supply lines are on poles overhead on the street. My meter is maybe 10-20 feet from the nearest pole and is fed by underground conduit. I think there is conduit on the pole that goes underground to feed my meter. The feed from the meter to the house is underground PVC (~200 feet). – kr4sh2 Jan 22 '22 at 01:52
  • National Grid US's [service specs](https://www.nationalgridus.com/media/pronet/constr_esb750.pdf), for reference – ThreePhaseEel Jan 23 '22 at 00:54
  • @kr4sh2 -- is converting this setup to not have the whole house transferred onto the generator an option? – ThreePhaseEel Jan 24 '22 at 04:38
  • @ThreePhaseEel That would be a pretty significant downgrade if we had to do that. I'd entertain any ideas you may have though. Is the meter at the street the biggest complication in your opinion? – kr4sh2 Jan 24 '22 at 06:19

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Your jurisdiction had not adopted the 2008 NEC when this installation was made, presuming that your service disconnecting means is located within the pedestal at the property line

What you have, provided that your utility agrees that the meter pedestal/post/rack at your property line is indeed your service equipment, is the "service dip" (underground service from overhead distribution) version of a rural "maypole" configuration, where a single metering point is designated on the property, and service entrances or feeders are run from there to the various outbuildings present. Given that you have a disconnecting means at your metering point and that this is recent construction, the wiring from it to your house is a feeder in all likelihood.

With that out of the way, were this to be built today, said feeder would be required by the NEC to have a separate equipment grounding conductor pulled with it, with the neutrals and grounds at the house's panel separated and the neutral bonding screw in that panel removed. However, in 2009, there's a chance that your jurisdiction had not yet adopted the 2008 NEC, which is the edition that deprecated grounding outbuilding feeders via the neutral, relegating it to an exception exclusive to existing installations. So, this could very well have been to local/state Code at the time it was inspected, although it would not have been to Code any longer after the AHJ's next adoption cycle took place.

That said, it's unclear in your configuration precisely where the bonding means for the building should go. Converting this to current Code, however, is not recommended, because it creates a single-point dependency on the integrity of the neutral-ground bond at the remote service equipment, and bonding the neutral of a stationary generator is not compatible with the transfer switches typically used in light-duty applications like yours. In particular, if your feeder was completely severed, resulting in a transfer to generator power, then since your generator's neutral is (and must be) floating, with a four-wire feeder from the pole to the house, there would be no neutral-ground bond in the system at that point, leading to a shock risk.

ThreePhaseEel
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  • If someone can come up with a way to bring this up to current Code standards without incurring the risk of a floating system if the feeder is completely severed, I'd like to hear it! – ThreePhaseEel Jan 24 '22 at 04:35
  • I understand what you mean by the shock risk if my 3 wire feeder were to be converted to 4 and there being no neutral+ground bond in the system if the feeder was severed. A SDS generator/ATS that bonds neutral and ground + switches neutral would solve that if I understand correctly (very expensive I think?). I'm wondering if there is a middle ground in regard to the ATS and the main panel. Could everything after the ATS could be 4 wire feeder, while keeping the 3 wire feeder to my ATS. Then bond everything in the ATS. If that improves anything? – kr4sh2 Jan 24 '22 at 08:09
  • @kr4sh2 given that the ATS is right next door to the house panel, moving the bond to the ATS doesn't change much about your setup (save for having to separate neutral and ground in the house panel itself), and yes, a SDS generator + switching neutral ATS would solve the issue, but at the cost of a rather more expensive ATS unfortunately – ThreePhaseEel Jan 24 '22 at 12:32
  • It seems so weird how the current code is so specific about where to bond neutral and here I am with 3 disconnects between the street and where my main panel bonds neutral again. I get it though... this is pre 2008 code across the board with the 3 wire feeder. Since non-SDS generator setups are common for residential, is the severed feeders situation not a worry for others because most people have the meter on their house versus mine is far away and subject to more potential hazards? – kr4sh2 Jan 24 '22 at 15:45
  • @kr4sh2 -- exactly. most people have the service disconnect on their house with its attendant neutral-to-ground bond, so the situation where a dropped feeder could sever the N-G bond while the generator tries to power the house up without it via the transfer switch isn't a concern for them – ThreePhaseEel Jan 24 '22 at 23:28